This invention relates generally to the utilization of solar energy cell technology as a source of electrical energy to charge batteries, and more specifically to charge batteries that are used in powering small electrical appliances, such as hearing aids, pocket calculators and the like.
The invention is most particularly concerned with a self-contained device having a solar cell power source that is capable of supplying electrical energy to recharge batteries placed within the container. The device is capable of supplying regulated, i.e., substantially constant-voltage electrical current for recharging the batteries by simply closing the container and placing the solar cell array disposed on the container in a location where it will receive incident light energy from either an artificial or natural light source.
Conventional battery recharging techniques utilize electrical energy from line voltage to supply a regulated supply of constant-voltage electrical current to the battery. Conventional line current sources require a transformer and a rectifying electronic circuit to convert to a constant-voltage electrical current and are inherently limited by requiring access to line current electrical sources. This presents a problem of incorporating a cumbersome and expensive circuit into a self-contained recharging unit and delimits the utility of any such unit to accessability to line current sources. Particularly with portable units utilized by travelers, such as those who have hearing aids, different countries have different plugs and different line voltages, such as to render inoperative conventional recharging apparatus designed for United States outlets and voltages.
Accordingly, it is the primary object of the present invention to provide a battery charging device in which the sole power source for recharging the battery or batteries is comprised of one or more solar energy cells, the device thereby being capable of supplying electrical energy to recharge the subject batteries for indefinite periods of time without recourse to any other source for electrical energy input.
It is a further object of the present invention to provide a battery charging device employing solar cells that supply a constant-voltage electrical current to the battery under varying lighting conditions.
It is a further object of the invention to provide a means to prevent discharging of a battery in the device when the container is in circuit open or circuit closed position.
Briefly, the invention in its broad aspect comprises a container having parts movable between open and closed positions, and an array of solar cells disposed on one of its surfaces. One part of the container is formed with a portion to receive at least one battery in a position in which it will be electrically connected--or disconnected to the solar array located in the other container part. The two container parts cooperate such that in container closed position an electrical circuit including the battery and the array is closed to charge the battery, and in container open position the electrical circuit including the solar cell array and the battery is broken.
More specifically, the parts of the container are a lid, in which the solar array can be mounted, and a tray that includes one or more battery receiving portions. As variants, closing the lid on which the solar array is mounted will make two contacts between the battery and the array to close the circuit, or one connection between the battery and the array is normally effected so that only a single contact need be made on closing of the lid.
Further objects, advantages, and features of the invention will be apparent in the arrangement and construction of the constituent parts of a specific embodiment of the best mode of the device as set forth in the following specification, taken together with the accompanying drawing.